Is "difficult" the new way of saying "taking responsibility"? Maybe they should signal that anyone coming in illegally will be rejected automatically and sent back. That's a really good way to deter any further illegal crossings.

Did Trump tell Trudeau to send out a tweet inviting smugglers and others to try the borders at illegal crossings?

No? Then the problem might've been started by Trump, but Trudeau certainly didn't help deter those people. Some might've been on the way already, sure, but when they heard that signal of welcome they all started the marathon over.